Can 6 years of hair loss from seborrheic dermatitis be reversed?

Without seeing your scalp, and knowing more about your story, I can't say what your diagnosis is. However, a few general points might help anyone with a similar experience. It is rare for most patients with seborrheic dermatitis to have massive hair loss.  It is fairly rare for patients treated for seborrheic dermatitis to have massive increases in hair density. It's true that seborrheic dermatitis can cause hair loss but it is usually a mild telogen effluvium. Exceptions do exist of course. Rarely, seborrheic dermatitis is associated with a scarring process that is not reversible (scarring seborrheic folliculitis). If seborrheic dermatitis is the sole cause of a person's non scarring hair loss and it is treated aggressively- that person will likely have signficant hair regrowth by 8 months post treatment. One of the most common reasons hair does not return back to normal in many treated for seb derm is the coexistence of unrecognized  androgenetic alopecia in the patient (or another coexisting diagnosis). All in all, keep close follow up with your physician.

Seborrheic dermatitis does not cause hair loss. In females, there are many causes that need to be evaluated through a good doctor including many blood bests.